How to discard the rest of the characters in a string?

Dear all:

I use fopen() and fgets() to read from a file line by line. I would like to extract the string in between, for example:

2013-123-00:12:11 xxxxxxxxxxxxxxxxx

"00:12:11" is the part I need to extract, any idea how I should go about it?

I can't use strstr() because the time changes in every line and I tried using strtok() but the result is not what I want.

Any help is appreciated, thanks.

hc

So what did you try with strtok()?
Post your attempt, and then we can tell you what you did wrong (so you learn).

> 2013-123-00:12:11 xxxxxxxxxxxxxxxxx
If you use " -" as the delimiter, then you extract in 3 calls
2013
123
00:12:11

I would use scanf for this. It has the advantage that it can tell you if a line is not properly formatted (OR if your format string is not specified correctly).

Example:

Code:

---

char buf[10000];
while (fgets(buf, 10000, stdin) != NULL) {   
    char mytime[100];
    if (sscanf(buf, "%*[^-]-%*[^-]-%99[^ ]", mytime) == 1) {
        printf("Mytime: %s\n", mytime);
    }
    else {
        printf("Unrecognized string!\n");
    }
}

---

Quote:

---

Originally Posted by Salem

So what did you try with strtok()?
Post your attempt, and then we can tell you what you did wrong (so you learn).

> 2013-123-00:12:11 xxxxxxxxxxxxxxxxx
If you use " -" as the delimiter, then you extract in 3 calls
2013
123
00:12:11

---

I tried with the delimiter ":" and the result was

2013-123-00
12
11

I'll take your suggestion using -, thanks.

hc

This works, thanks, but there were some weird numbers in between, I'll fix it, thanks very much.

hc

Quote:

---

Originally Posted by c99tutorial

I would use scanf for this. It has the advantage that it can tell you if a line is not properly formatted (OR if your format string is not specified correctly).

Example:

Code:

---

char buf[10000];
while (fgets(buf, 10000, stdin) != NULL) {   
    char mytime[100];
    if (sscanf(buf, "%*[^-]-%*[^-]-%99[^ ]", mytime) == 1) {
        printf("Mytime: %s\n", mytime);
    }
    else {
        printf("Unrecognized string!\n");
    }
}

---

---

Hi, Guys, problem solved, below is the source code, in case anyone running into the same problem, any suggestion to make it "prettier" is appreciated, thanks again.

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define SIZE 50
#define CROPPED_SIZE 10

/* function prototype */
char * RemoveColon (char *dest, const char *src);

int main (int argc, char **argv) {
        /* define buffer space for the file */
        char string[SIZE];
        char croppedString[SIZE];
        FILE *pfile;
        int i, previousNum=0, counter=0, timeGap;
        char mytime[CROPPED_SIZE];
        char *croppedTime = mytime;

        /* open the existing file from input */
        pfile = fopen (argv[1], "r");

        while (fgets (string, SIZE, pfile) != NULL) {
                strcpy (croppedString, string);
                /* using sscanf to extract the string */
                if (sscanf(croppedString, "%*[^-]-%*[^-]-%20[^ ]", mytime) == 1) {
                        /* zero out the unwanted characters */
                        for (i=18; i<SIZE; i++) {
                                croppedString[i] = '\0';
                        }
                        croppedTime = RemoveColon (croppedTime, mytime);
                        int convertedNum = atoi(croppedTime);
                        timeGap = convertedNum - previousNum;
                        if (timeGap < 0) {
                                convertedNum = convertedNum + 240000;
                                timeGap = convertedNum - previousNum;
                        }
                        if ((timeGap >= 10000) && (previousNum != 0)){
                                counter++;
                                printf("%s\n", string);
                        }
                        previousNum = convertedNum;

                }
        }

        fclose (pfile);

        return 0;
}


char * RemoveColon (char *new, const char *str) {
        const char *p;
        char *q;
        for (p=str, q=new; *p != '\0';) {
                if (*p != ':') {
                        *q = *p;
                        p++;
                        q++;
                } else {
                        p++;
                }
        }
        *q = '\0';
        return new;
}

---

Thanks.

hc

Code:

---

                        /* zero out the unwanted characters */
                        for (i=18; i<SIZE; i++) {
                                croppedString[i] = '\0';
                        }
                        croppedTime = RemoveColon (croppedTime, mytime);
                        int convertedNum = atoi(croppedTime);

---

I don't know why you need any of this.
hh:mm:ss should be stored in mytime, as a direct result of the sscanf call.

Because I need to be able to compare and subtract the time with the previous string (record) ...

Quote:

---

Originally Posted by Salem

Code:

---

                        /* zero out the unwanted characters */
                        for (i=18; i<SIZE; i++) {
                                croppedString[i] = '\0';
                        }
                        croppedTime = RemoveColon (croppedTime, mytime);
                        int convertedNum = atoi(croppedTime);

---

I don't know why you need any of this.
hh:mm:ss should be stored in mytime, as a direct result of the sscanf call.

---

I'm not entirely sure what output you want but you're working too hard to get it.

Code:

---

#include <stdio.h>
#include <ctype.h>

int main(void) {

  char s[]={"2013-123-00:12:11 xxxxxxxxxxxxxxxxx"};
  char raw[10]={""};
  char data[10]={""};
  int i,j,n1,n2;
  sscanf(s, "%d%d%s",&n1,&n2,raw);

  printf("%d %d raw: %s\n",n1,n2,raw);
  for(i=0,j=0;raw[i];i++) {
      if(isdigit(raw[i])) {
        data[j]=raw[i];
        ++j;
      }
  }
  data[j]='\0';
  printf("\ndata: %s\n",data);

  return 0;
}

---

Yes, you are right ...

I changed it and it looks better now, thanks for the tip!

hc

Quote:

---

Originally Posted by Adak

I'm not entirely sure what output you want but you're working too hard to get it.

Code:

---

#include <stdio.h>
#include <ctype.h>

int main(void) {

  char s[]={"2013-123-00:12:11 xxxxxxxxxxxxxxxxx"};
  char raw[10]={""};
  char data[10]={""};
  int i,j,n1,n2;
  sscanf(s, "%d%d%s",&n1,&n2,raw);

  printf("%d %d raw: %s\n",n1,n2,raw);
  for(i=0,j=0;raw[i];i++) {
      if(isdigit(raw[i])) {
        data[j]=raw[i];
        ++j;
      }
  }
  data[j]='\0';
  printf("\ndata: %s\n",data);

  return 0;
}

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